Human Systemic Immune Response to Ingestion of the Oral Probiotic Streptococcus salivarius BLIS K12.

Streptococcus salivarius K12 is an oral probiotic known to contribute to protection against oral pathogenic bacteria in humans. Studies of immune responses to S. salivarius K12 have focused on the oral cavity, and systemic immune responses have not yet been reported. The aim of this study was to identify acute systemic immune responses to the commercial product, S. salivarius BLIS K12, in a double-blinded, placebo-controlled human clinical trial. It was hypothesised that consumption of S. salivarius BLIS K12 would induce an anti-inflammatory response and a decrease in pro-inflammatory cytokines. Blood samples were obtained from participants prior to a single dose of S. salivarius BLIS K12 or a placebo and then secondary blood samples were obtained 24 h and 7 days post-consumption. Samples were analysed using multi-parametric flow cytometry, to quantify immune cell frequency changes, and by a LEGENDplex assay of human inflammatory cytokines. Consumption of S. salivarius BLIS K12 was associated with increased levels of IL-8 at 24 h. The frequency of Tregs increased in samples taken 7 days after probiotic consumption, and IL-10 concentrations were higher at 7 days than 24 h after consumption. There was no difference in the frequency and/or activation of CD4+ T cells, CD8+ T cells, B cells and NK cells. Interestingly, there was an increase in IL-12, 7 days after the consumption of S. salivarius BLIS K12. Collectively, this research demonstrates that ingestion of the probiotic S. salivarius K12 can induce changes in the systemic immune response. The implications of the generation and type of immune response warrant further study to determine potential health benefits.

Bacteriotherapy for preventing recurrent upper respiratory infections in children: a real-world experience.

Background Recurrent upper respiratory infections (RURI) constitute a social problem for both their pharmaco-economic impact and the burden for the family. Bacteriotherapy could be an interesting preventive option. Objective The aim of this study was to evaluate the preventive effects of RURI in children. Design The study was designed as spontaneous, and was conducted in real-life seting. Globally, 80 children (40 males, mean age 5.26 (2.52) years) with RURI were enrolled. Children were treated with Streptococcus salivarius 24SMB and Streptococcus oralis 89a: nasal spray 2 puffs per nostril twice/day for a week for 3 monthly courses. Number of URI, and school and work absences were evaluated and compared with the past year. Results Bacteriotherapy significantly halved the mean number of URI episodes being 5.98 (2.30) in the past year and 2.75 (2.43) after the treatment (p<0.0001). Bacteriotherapy also induced an over 35% reduction both in the number of school days and in the number of working days missed per month from 4.50 (2.81) to 2.80 (3.42) and from 2.33 (2.36) to 1.48 (2.16) respectively (p<0.0001). Conclusions This and real-life study provides the first evidence that Streptococcus salivarius 24SMB and Streptococcus oralis 89a nasal spray could be effective in preventing RURI in children.

Streptococcus salivarius-mediated CD8+ T cell stimulation required antigen presentation by macrophages in oral squamous cell carcinoma.

It has been shown that the peripheral blood mononuclear cells (PBMCs) from oral squamous cell carcinoma (OSCC) patients presented cytotoxic CD8 T cell response against Streptococcus salivarius (S. salivarius), of which the frequency was positively associated with recurrence-free survival in OSCC patients. To identify the conditions required for regulating S. salivarius-specific CD8 T cell-mediated cytotoxicity, we selectively depleted individual components of the PBMCs, and observed that the depletion of monocytes/macrophages, but not other immune cell subsets, significantly downregulated the S. salivarius-specific CD8 T cell cytotoxicity. Monocyte/macrophage alone was sufficient to reconstitute optimal granzyme B expression from S. salivarius-specific CD8 T cells. Also, both the memory and the naive CD8 T cells reacted to S. salivarius-stimulation, with the memory CD8 T cells presenting significantly higher S. salivarius-reactivity. Using M1- and M2-polarized macrophages from circulating monocytes, we found that M1-polarized macrophages, with significantly higher IL-12 expression and significantly lower IL-10 and MHC class II molecule expression, was more effective at promoting granzyme B responses in CD8 T cells, and required CD80/CD86 costimulating molecules for optimal responses. Interestingly, the tumor-associated macrophages (TAMs) from resected tumors presented characteristics of M2-polarized macrophages with high MHC class II expression and low IL-12 secretion. The frequency of tumor-infiltrating S. salivarius-specific cytotoxic CD8 T cell was inversely correlated with the level of IL-10 secretion and the MHC class II molecule expression in autologous TAMs. Together, we demonstrated that monocyte/macrophages presented essential antigen-presentation and costimulatory roles in CD8 T cell-mediated S. salivarius-specific granzyme B responses, and the polarization of macrophages could influence the potency of CD8 T cell responses.

Upregulation of bacterial-specific Th1 and Th17 responses that are enriched in CXCR5+CD4+ T cells in non-small cell lung cancer.

The microbial community in the mucosal surfaces is involved in the development of human cancers, including gastric cancer and colorectal cancer. The respiratory tract in the lung also hosts a distinctive microbial community, but the correlation between this community and lung cancer is largely unknown. Here, we examined the Th1 and Th17 responses toward several bacterial antigens, in CD4+ T cells sourced from the peripheral blood (PB), the lung cancer (LC) tissue, and the gastrointestinal (GI) tract of non-small cell lung cancer (NSCLC) patients. Compared to healthy controls, the NSCLC patients presented significantly higher frequencies of Th1 and Th17 cells reacting to Streptococcus salivarius and S. agalactiae, in the PB, LC, and GI tract. Further investigation showed that the upregulation in anti-bacteria response was likely antigen-specific for two reasons. Firstly, the frequencies of Th1 and Th17 cells reacting to Escherichia coli, a typical GI bacterium, were not upregulated in the PB and the LC of NSCLC patients. Secondly, the S. salivarius and S. agalactiae responses could be partially blocked by Tü39, a MHC class II blocking antibody, suggesting that antigen-specific interaction between CD4+ T cells and antigen-presenting cells was required. We also found that S. salivarius and S. agalactiae could potently activate the monocytes to secrete higher levels of interleukin (IL)-6, IL-12, and tumor necrosis factor, which were Th1- and Th17-skewing cytokines. Interestingly, whereas CXCR5+CD4+ T cells represented <20% of total CD4+ T cells, they represented 17%-82% of bacteria-specific Th1 or Th17 cells. Together, these data demonstrated that NSCLC patients presented a significant upregulation of bacterial-specific Th1 and Th17 responses that were enriched in CXCR5+CD4+ T cells.